Fuel and inlet guide vane control for a free turbine engine



Sept. 25, 1962- J. LlSTON 3,055,177

FUEL AND INLET GUIDE VANE CONTROL FOR A FREE. TURBINE ENGINE Filed Jan. 4. 1960 2 Sheets-Sheet 1 fuel I Ca/V TROL I INVENTOR. JoSfPl-l 41s To,

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3,055,177 FUEL AND INLET GUIDE VANE CONTROL FOR A FREE TURBINE ENGINE Filed Jan. 4, 1960 J. LISTON Sept. 25, 1962 2 Sheets-Sheet 2 mmvron. Joan /11s 7mg 3,055,177 FUEL AND INLET GUIDE VANE CONTROL FOR A FREE THNE ENGEQE Joseph Liston, 900 Robinson St, West Lafayette, ind. Filed Jan. 4, 1960, Ser. No. 220 7 Claims. (Cl. 6039.16)

This invention relates to power plants embodying a gas-turbine and a gas-source comprising a burner supplied with air from a compressor. The invention isv particularly concerned with such a power plant in which operating conditions require wide variation in the power delivery of the turbine and in which the gas source is controlled jointly with the turbine so that its output will be proportioned to the demands of the turbine. It is the principal object of the invention to provide for apparatus of the kind mentioned a control means which will permit selective regulation of the turbine and gas source While, at the same time, imposing on regulation of the gas source limits protecting the apparatus against temperatures and/or speeds so high as to involve the possibility of damage or danger.

In carrying out the invention I employ a valve which regulates the supply of fuel to the gas source and I provide for such valve a control means operated jointly by two different mechanisms. One of such mechanisms, which also controls the turbine and may be designated as the primary control, is adapted for manual or automatic operation to regulate jointly the performance of the turbine and gas-source. The other mechanism is arranged to be automatically responsive to temperature and/or speed conditions. The latter mechanism, which may be designated as the secondary control, is preferably responsive to both temperature and speed and serves to impress on the primary control an overriding control which will operate, irrespective of the setting of the primary control, to reduce the supply of fuel to the gas source whenever either temperature or speed becomes excessive.

In the preferred form of apparatus, the fuel valve is operated by a movable member which can be moved in a valve-opening or valve-closing sense by either the primary or the secondary control independently of the other. The secondary control embodies a fluid-pressure past a valve controlled by temperature of the gas-source burner. The arrangement is such that the motor will respond to either excessive compressor speed or excessive burner temperature to move the fuel-controlling valve toward closed position irrespective of the condition of adjustment of the primary control.

Other objects and features of the invention will become apparent from the following more detailed description and from the accompanying drawings, in which:

FIG. 1 is a diagrammatic View showing a power plant including a gas turbine and a gas-source therefor;

FIG. 2 is a sectional view illustrating the fuel-regulating valve and one form of controlling mechanism therefor;

FIG. 3 is a diametric view of a portion of the con trolling mechanisms shown in FIG. 2; and

FIG. 4 is a sectional view of another form of mechanism for controlling the fuel valve.

The system shown in FIG. 1 comprises a reversible gas turbine 10 whose direction of rotation and speed are States Patent M 3,d55,l77 Patented Sept. 25, 1952 turbine and its control are of the type more fully set forth and described in my copending application Serial No. 690,037, filed October 14, 1957. Gas for the turbine is supplied by a generator comprising a compressor 15, a burner 16, and a compressor drive turbine 17 operatively connected to the compressor 15 as through a shaft 18. Air compressed in the compressor 15 is delivered through a conduit 20 to the burner 16, where it is heated by the combustion of fuel supplied to the burner through a conduit 21. The products of combustion and the heated air from the burner 16 pass through a conduit 22 to the compressor drive turbine 17 and thence through a conduit 23 to the turbine 10. Gas generators of this type are well known and need not be further described.

As set forth above, this invention is directed toward a means for preventing overloads and damage to the gas generator. To this end, fuel flow to the burner 16 through the conduit 21 is controlled jointly in accordance with the position of the turbine-controlling cam 12, the rotational speed of the gas-generator unit, and the temperature produced by the burner 16. For this purpose I provide control mechanism, designated in its entirety by the reference numeral 24 in FIG. 1, such control mechanism being operatively connected to the cam 12. Response of the control mechanism 24 to the speed of the gas-generator is conveniently effected by transmitting the outlet pressure of the compressor 15 to the control mechanism 24 through a conduit 25. Operation of the control mechanism 24 in response to the temperature generated by the burner 16 is shown as effected through means including a temperature-responsive bleed valve 26 mounted on the burner housing and connected to the control mechanism 24 through a conduit 27.

The control mechanism indicated diagrammatically at 24 may be of the type more fully illustrated in FIGS. 2 and 3. As will be clear from FIG. 2 such mechanism comprises a housing 30 provided with a cylinder bore 31 which slidably receives a piston 32. The piston 32 has a shank 33 which projects outwardly through the end of the bore 31 and into a cylinder 34 rigidly mounted on the housing 30. Within the cylinder 34, a piston 35 is mounted on the shank 33, and both of the rigidly interconnected pistons are urged toward the right by a compression spring 36 located in the cylinder 34 and acting against the piston 35.

The inner (left) and outer (right) ends of the cylinder bore 31 are both connected to the conduit 25, as is also the outer end of the cylinder 34. The inner end of the cylinder bore 31 is also connected to the conduit 27 leading to the thermostatically controlled bleed valve 26. As shown in FIG. 2, the valve 26 comprises a housing 40 the interior of which communicates, under the control of a valve member 41, with the conduit 27. The valve member 41 is controlled in response to the temperature of the burner housing 16, conveniently by mounting it on the free end of a bimetallic strip 42 secured in heattransmitting relationship with the burner housing, preferably adjacent the outlet end thereof. The valve member 41 is normally maintained closed by a spring 43 located within the valve housing 40, and the housing 40 is provided with one or more vent openings 44 to permit the escape of gases entering the housing when the valve member 41 is open.

a By the arrangement just set forth the axial position of the p1ston-unit 32-35 is made responsive'in a manner hereinafter described jointly to the speed of the gas ports a pair of rigidly interconnected gears 47 and 48. The gears 47 and 48 are located in fixed axial position on the rod 46 as by means of collars 46' secured to such rod. The gear 48 meshes with a gear 49 rigidly mounted on a shaft 50 which operates a valve controlling the rate of fuel supply through the conduit 21 to the burner 16. In the particular arrangement illustrated, it is contemplated that the burner 16 will be supplied with a gaseous fuel-air mixture, and the shaft 50 is therefore shown in FIG. 2 as extending into and across the conduit 21 and provided therein with a valve 51 of the butterfly type. It will of course be understood, however, that this invention is not limited with respect to the type of fuel used in the burner nor to any particular means for regulating the rate of fuel supply.

To control the rotational position of the gears 47-48 about the axis of the rod 46, the gear 47 is operatively connected (FIG. 3) to the cam 12. As shown, the gear 47 is a helical gear meshing with a gear or gear sector 53 fixedly secured to a shaft 54 which carries at its upper end an arm 55 having a cam follower 56 received in a groove 57 in the cam 12. Since the gear 47 is a helical gear, it can be rotated about its axis either by axial movement (gear 53 being stationary) or by rotation of the gear 53 which drives it. Thus, the valve 51 will respond to both axial movement and rotation of the gears 4748.

The apparatus above described operates in the following manner: FIGS. 2 and 3 illustrate the condition existing under normal operating conditionsi.e., when the speed of the gas generator and the temperature of the burner 16 are below their respective predetermined maximum values. Under these'conditions, the valve 41 is closed, and the fluid pressure at the outlet of the compressor is transmitted through conduit 25 to both ends of the cylinder bore 31 and to the right-hand end of the cylinder 34. The fluid pressure in the opposite ends of the cylinder bore 31 acts oppositely on the piston 32 and therefore is without effect in influencing movement of such piston. The pressure in the right-hand end of the cylinder 34, however, is opposed only by the spring 36, as the left-hand end of the cylinder 34 is vented to atmosphere as indicated at 38. As long as this normal operating condition obtains, the position of the gas-controlling valve 51will be controlled in response to operation of the cam 12, any rotation of which is transmitted through the arm 55, shaft 54, and gear 53 to the gears 47-48 and thence, through gear 49 and shaft 50 to the valve 51. When the speed of the-gas generator exceeds the predetermined maximum, the increased pressure at the outlet of the compressor 15, acting through conduit 25 in the right-hand end of the cylinder 34, overcomes the spring 36 and moves the pistons 32 and 35 and the rod 46 to the left. The gear 47 moves axially with the rod and hence is rotated about the rod-axis to rotate the gears 48 and 49 and move the valve 51 toward closed position.

If, at any time, the 'burner 16 becomes overheated, the bimetallic strip 42 will fiex to open the valve 41, thus permitting flow from the conduit 25 through a restricting orifice 58, across the left-hand end of the cylinder bore 31, and thence through conduit 27, past the valve 41 and to the atmosphere by way of the openings 44 in the housing 40. As a result of this flow of air, static fluid pressure within the left-hand end of the cylinder becomes reduced by the pressure drop across the orifice 58. Relieved at least to some extent of the rightward effort exerted on the piston 32 by pressure in the left-hand end of the cylinder bore 31, the piston unit 32-35 and rod 46 move to the left to cause rotation of the gear 47 and partial closing of the valve 51, just as Was the case when such leftward movement resulted from overspeeding of the gas generator.

. As shown in FIGS. 2 and 3, the gears 48 and 49 are spur gears. This is not essential, however, as they might be helical gears. However, if the gears 48 and 49 are helical gears, they should be of dilferent pitch or different hand from the gear 47, as otherwise axial movement of the rod 46 would not result in rotation of the gear 49 and valve-controlling shaft 50. Obviously, both of the gears 47 and 48 must have a face width great enough to maintain them in mesh respectively with the gears 53 and 49 throughout the full extent of movement of the shaft 46.

In the modified control mechanism shown in FIG. 4 the pistons 32 and 35 are replaced by flexible diaphragms 60 and 61 respectively dividing two chambers 62 and 63 provided in a housing 64. The two diaphragms 60 and 61 are interconnected by a rod 65 having an axial passage 66 which provides intercommunication of the right-hand compartments of the two chambers 62 and 63. The lefthand compartment of the chamber 62 communicates through a flow-restricting orifice 67 with the conduit 25 and also communicates with the conduit 27 the outlet of which, as before, is controlled by the thermostatically regulated valve. The left-hand compartment of the chamber 63 is vented as at 68, while the right-hand compartment of such chamber communicates with the conduit 25. A rod 70 rigidly connected to the diaphragm 60 extends outwardly through the end of the housing 64, where it is surrounded by a compression spring 71 which, acting between a collar 72 fixed on the rod 76 and a stationary yoke 73, urges the rod and the diaphragms to the right. Rightward movement of the rod 70 and the diaphragms is limited by engagement of the collar 72 with the end of the housing 64.

The outer end of the rod 70 is pivotally connected by a pivot pin 75 to an intermediate point of a lever 76 having slots 77 and 78 in its opposite ends. The slot 77 receives a pin 79 fixed at the outer end of an arm 80 secured to the valve shaft 50. The slot 78 of the lever 76 receives a pin 81 secured at the outer end of one of the arms of a bell crank 82 pivoted at 83. The other arm of the bell crank 82 carries a cam follower 84 received in the cam groove 57 of the control cam 12.

Under normal operating conditions, when the speed of the gas generator and the temperature of burner 16 are below their respective maximum values, the cam 12 can be rotated to vary the speed of the turbine and, at the same time, to control the bell crank 82. Movement of the bell crank is transmitted through the lever 76 to the arm 80 and valve-shaft 50. Outlet pressure of the compressor 15 is applied to the left-hand compartment of chamber 62, to the right-hand compartment of chamber 63 and, through the passage 66, to the right-hand compartment of chamber 62. The pressures in the two compartments in chamber 62 thus balance each other and are without effect on the position of rod 70, irrespective of variations in the outlet pressure of the compressor 15. However, the pressure in the right-hand compartment of chamber 63 is opposed only by the spring 71; and if, as the result of increasing speed, the outlet pressure of the compressor 15 becomes too great the increased pressure in the right-hand compartment of chamber 63 will force the diaphragms and the rod 70 to the left. In this situation, the lever 76 acts as a lever of the third class, being pivoted at 81 and swinging counterclockwise to swing the arm 80 and rotate the valve shaft 50in valve-closing direction.

If the burner 16 becomes overheated, the conduit 27 becomes vented to atmosphere, thus permitting flow through the left-hand compartment of chamber 62 from the conduit 25 to the conduit 27. The rightward pressure on the diaphragm 60 is thus relieved to the extent of the pressure drop across the orifice 67 and the rod. 70 moves 7 O to the left under the predominating pressures on the right- It may be noted that while the above descriptions of operation refer to movement of the rod 46 or 70 only as occurring under abnormal conditions, the fact is that each of such rods may move to some extent when normal operating conditions obtain. Thus, in response to movement of the. control cam 12, the outlet pressure of the compressor 15 will vary and may react on the control mechanism 24- to cause some movement of the rod 46 or 70. However, until the pressure at the outlet of the compressor reaches the predetermined maximum safe value, such movement of the rod is insuflicient to fully offset manual control of the valve 51 by movement of the control cam 12.

I claim as my invention:

1. In combination, a gas turbine; a gas-source therefor, said gas-source comprising a burner, a compressor delivering air to said burner, and a compressor drive turbine receiving hot gases from said burner and operatively connected to said compressor; a conduit for conveying gases from said compressor drive turbine to said gas turbine; regulating means for regulating flow of gases through said conduit; means responsive to temperature generated by said burner; means responsive to the speed of said compressor; a first movable member movable to regulate the supply of fuel to said burner; a second movable member operatively connected to one of said three means to be moved thereby; a third movable member controlled in position jointly by the other two of said three means; and a device operatively connecting said first member with both said second and third members to cause said first member to move under joint control by said second and third members.

2. In combination, a gas turbine; a gas-source therefor, said gas-source comprising a burner, a compressor delivering air to said burner, and a compressor drive turbine receiving hot gases from said burner and operatively connected to said compressor; a conduit for conveying gases from said compressor drive turbine to said gas turbine; regulating means for regulating flow of gases through said conduit; means responsive to temperature generated by said burner; a bleed conduit connecting the outlet of said compressor to atmosphere; a bleed valve operatively connected to said temperature responsive means for controlling flow through said bleed conduit; pressure-responsive means responsive to fluid pressure at a point in said conduit between said compressor and said bleed valve; and means controlled jointly by said regulating means and said pressure-responsive means for regulating the supply of fuel to said burner.

3. In combination, a gas turbine; a gas-source therefor, said gas-source comprising a burner, a compressor delivering air to said burner, and a compressor drive turbine re ceiving hot gases from said burner and operatively connected to said compressor; a conduit for conveying gases from said compressor drive turbine to said gas turbine; a first regulating means for regulating flow of gases through said conduit; a second regulating means for regulating the supply of fuel to said burner; and an operative connection between said two regulating means; said operative connection including means which is responsive to temperature generated by said burner, and which acts on the second regulating means and reacts on the first regulating means to make the second regulating means responsive jointly to the setting of the first regulating means and the temperature generated by the burner and to effect temperature-responsive adjustment of the second regulating means without disturbing the setting of the first regulating means.

4. In combination, a gas turbine; a gas-source therefor, said gas-source comprising a burner, a compressor delivering air to said burner, and a compressor drive turbine receiving hot gases from said burner and operatively connected to said compressor; a conduit for conveying gases from said compressor drive turbine to said gas turbine; a

first regulating means for regulating flow of gases through said conduit; a second regulating means for regulating the supply of fuel to said burner; and an operative connection between said two regulating means, said operative connection including means which is responsive to the speed of said compressor, and which acts on the second regulating means and reacts on the first regulating means to make the second regulating means responsive jointly to the setting of the first regulating means and the speed of the compressor and to etfect speed-responsive adjustment of the second regulating means without disturbing the setting of the first regulating means.

5. In combination, a gas turbine; a gas-source therefor, said gas-source comprising a burner, a compressor delivering air to said burner, and a compressor drive turbine receiving hot gases from said burner and operatively connected to said compressor; a conduit for conveying gases from said compressor drive turbine to said gas turbine; regulating means for regulating flow of gases through said conduit; means for regulating the supply of fuel to said burner; two mating helical gears operatively connected respectively to said two regulating means; and means responsive to temperature generated by said burner for moving one of said gears axially of itself to vary, through the interaction of the teeth of said two helical gears, the phase relationship of those gears with regard to their positions about their respective axes and thereby alter the relation between the settings of said two regulating means.

6. In combination, a gas turbine; a gas-source therefor, said gas-source comprising a burner, a compressor delivering air to said burner, and a compressor drive turbine receiving hot gases from said burner and operatively connected to said compressor; a conduit for conveying gases from said compressor drive turbine to said gas turbine; regulating means for regulating flow of gases through said conduit; means for regulating the supply of fuel to said burner; two mating helical gears operatively connected respectively to said two regulating means; and means responsive to the speed of said compressor for moving one of said gears axially of itself to vary, through the interaction of the teeth of said two helical gears, the phase relationship of those gears with regard to their positions about their respective axes and thereby alter the relation between the settings of said two regulating means.

7. In combination, a gas turbine; a gas-source therefor, a first conduit for supplying fuel to said gas-source, a second conduit for conveying gases from the gas-source to the turbine, flow-regulating means in each of said conduits, a movable control member operatively connected to the flow-regulating means in said second conduit, a rotatable shaft operatively connected to said control memher, a pair of helical gears operatively interconnecting said shaft and the flow-regulating means in the first conduit, and means controlled by said gas-source for moving one of said helical gears axially of itself to vary, through the interaction of the teeth of said two helical gears, the phase relationship of those gears with regard to their positions about their respective axes and thereby alter the relation between the position of said shaft and the setting of said flow-regulating means.

References Cited in the file of this patent UNITED STATES PATENTS 2,625,789 Starkey Ian. 20, 1953 2,715,814 Barr Aug. 23, 1955 2,912,824 Van Nest et al Nov. 17, 1959 2,946,189 Basford July 26, 1960 2,958,186 Mock Nov. 1, 1960 2,959,002 Best Nov. 8, 1960 FOREIGN PATENTS 1,022,653 France Dec. 17, 1952 

